收藏本站
Appendix A: Hardware Reference Manual
for the pre-driver provides better response for turning on and off current flow in the ignition coil. The
MC33812 can be configured to drive either of the two most popular choices for the external transistor: the
IGBT or the Darlington transistor. Historically, the Darlington transistor was the most popular choice for
the ignition driver transistor. The newer solution is the IGBT, but until recently, it was considerably more
expensive than the Darlington. The choice now depends on what the designer prefers and what it more
readily available. The reference design uses an IGBT to control the ignition circuit with no provision to
configure for Darlington. Further design considerations are included in the Discrete IGBT Driver section
below.
For the MC33812, the IGNIN signal is the logic level input that is controlled by the MCU. There is also an
input pin to select either the 5 Volt supply or the 12 Volt supply as the source voltage supply for the ignition
pre-driver. This input is the IGNSUP pin. If the designer chooses to use an IGBT, then IGNSUP must be
connected to 12 Volts to provide the necessary gate drive voltage needed to enhance the gate of the
IGBT. When using a Darlington, the IGNSUP pin must be connected to the 5 Volt supply to avoid
unnecessary power dissipation in the MC33812 when providing the 50 mA of base current drive. The
logic function through the pre-driver is non-inverting, meaning that a high logic level on IGNIN will turn on
the IGNOUTH output stage and a low on IGNIN will turn on the IGNOUTL stage. The addition of the driver
transistor makes the overall logic function inverting. The IGNFB pin is an input that is tied to the collector
of the IGBT or Darlington through a 10:1 resistor divider. The IGNFB is used to monitor the voltage on the
collector to check for a shorted ignition coil, or other short to battery conditions. The resistor divider is
needed because the voltage on the collector can reach 400 Volts due to inductive flyback from the ignition
coil. The divider keeps this flyback voltage down to 40 Volts to protect the input of the MC33812 from over
stress. Components of the feedback circuit should be selected to work with the components of the
ignitions system. If the IGBT breakdown voltage is different from 400 V, changing the resistor divider is
necessary to create the proper ratio that protects the IGNFB pin and create thresholds that properly
indicate faults.
10.4.2.7
10.4.2.7.1
ISO-9141 Transceiver
Design Criteria
For small engines, the number of electronic modules is typically very limited. In most cases, the engine
controller may be the only ECU. While communication to other ECUs is not apart of normal operation, it
is typically required to provide diagnostic communication to troubleshoot the system. The ISO-9141, also
known as a “K-Line” interface, allows bi-directional serial communications between the MCU and an
external master device. It is typically used to convey diagnostic messages between MCU and an external
diagnostic code reader. A common small engine implementation will use ISO-9141 specifications as the
physical transport layer for communication between the ECU and the diagnostic tool. ISO-9141 is a good
choice as it is a single wire interface and protocols are based on a UART functionality commonly found
on most MCUs. Connectivity is also robust as it uses battery level signals.
10.4.2.7.2
Implementation Recommendations
Integrated into the MC33812 is an ISO-9141 transceiver. The MTX and MRX pins are the logic level input
and output pins, respectively, that connect this block to the SCI port of the MCU. The ISO-9141 pin is a
0 to battery voltage interface pin with an active pull down MOSFET and a passive pull-up resistor of
1.0 kOhm. In the reference design, this I/O is also protected from reverse battery by a diode and from
transients with a capacitor and a 24 Volt TVS.
Beyond the ISO-9141 communication, provision for adding connectivity to a CAN transceiver has been
provided on the reference design. The 4-pin header label “CAN1” provides power and ground
connections as well as CANTX and CANRX connections back to the MCU. This allows future expansion
and connectivity to a CAN bus containing multiple ECUs. The use of CAN in a small engine system will
become more important as electronic content increases.
Small Engine Reference Design User Manual , Rev. 3.0
Freescale Semiconductor
49
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
KIT33812EKEVBE BOARD EVALUATION FOR MC33812
KIT33879AEKEVBE BOARD EVALUATION FOR MC33879
KIT33880DWBEVB KIT EVAL FOR MC33880 8X SW W/SPI
KIT33886DHEVB KIT EVAL FOR MC33886 H-BRIDGE
KIT33887EKEVBE BOARD EVALUATION FOR MC33887
KIT33887PNBEVB KIT EVAL 33887 5A H-BRIDGE PQFN
KIT33905D5EKEVBE KIT EVALUATION FOR MC33905
KIT33912EVME KIT EVALUATION FOR MC33912
相关代理商/技术参数
KIT33812ECUEVME 制造商:Freescale Semiconductor 功能描述:Small Engine Control Reference Design
KIT33812EKEVBE 功能描述:电源管理IC开发工具 INTEGRATED DUAL LOW & HI RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
KIT33813AEEVBE 功能描述:电源管理IC开发工具 2 Cylinder Small Engine RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
KIT33814AEEVBE 功能描述:交换机 IC 开发工具 2 Cylinder Small Engine RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:USB Power Switches 工具用于评估:MAX4984E 工作电源电压:2.8 V to 5.5 V
KIT33816AEEVM 功能描述:电源管理IC开发工具 Engine Control Module RoHS:否 制造商:Freescale Semiconductor 产品: 类型: 工具用于评估: 输入电压: 输出电压:
KIT33879AEKEVBE 功能描述:电源管理IC开发工具 CONFIGURABLE OCTAL RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
KIT33880DWBEVB 功能描述:电源管理IC开发工具 33880DWB COSS KIT RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
KIT33883DWEVB 功能描述:KIT EVAL FOR MC33883 PRE-DRIVER RoHS:否 类别:编程器，开发系统 >> 过时/停产零件编号 系列:- 标准包装:1 系列:- 传感器类型:CMOS 成像，彩色（RGB） 传感范围:WVGA 接口:I²C 灵敏度:60 fps 电源电压:5.7 V ~ 6.3 V 嵌入式:否 已供物品:成像器板 已用 IC / 零件:KAC-00401 相关产品:4H2099-ND - SENSOR IMAGE WVGA COLOR 48-PQFP4H2094-ND - SENSOR IMAGE WVGA MONO 48-PQFP